The present invention relates to a method for changing the supply of characters in the character generator of an ideographic typewriter which contains data for controlling a device for the display of such characters.
In order to permit machine processing of characters for display by means of a printer or for projection on a video screen, the data for the characters must be contained in a character memory or character generator of the machine. For alphabetic scripts this requires only a small amount of memory space. But the memory space becomes quite a problem when ideographic scripts which employ an extensive supply of characters are to be processed.
In the case of the Chinese script, for example, even if the simplified Chinese telegraph code were used, approximately 10,000 ideograms would have to be stored in the character generator, and up to 50,000 ideograms to cover all of the characters of the language. The problem becomes even more difficult to solve because some of the ideograms have very complicated designs which, particularly if the display is to have high accuracy and resolution, can be represented only by a large number of data bits.
Known methods attempt to solve this problem by separating the ideographic symbols into components and storing them in that form. Since the selected components are the basic building blocks for the ideographic characters, a larger supply of characters with comparatively few stored components can be contained in a character generator of such design. The call-up of the ideograms is then effected by suitable addresses assigned to individual components from which the finished ideographic character is composed within a standard character area, or space. For this purpose it has also been proposed to provide a single character display on which the components addressed by the operator are displayed until the desired ideographic character has been assembled.
But such a measure as well, which, due to the possibilities of multiple use of components for different characters, may involve a large amount of characters in a character generator of given size, does not permit the storage of even half of the 50,000 ideograms of, for example, the Chinese script.